Biology subjects

Jelinkova, A.

Publications and source records attributed to Jelinkova, A..

3 recordsLinked to original sources

bioRxiv2023

Ectopic assembly of an auxin efflux control machinery shifts developmental trajectories

Polar auxin transport in the Arabidopsis root tip maintains high auxin levels around the stem cell niche that gradually decrease in dividing cells but increase again once they transition towards differentiation. Protophloem differentiates earlier than other proximal tissues and employs a unique auxin canalization machinery that is thought to balance auxin efflux with retention. It consists of a proposed activator of PIN auxin efflux carriers, the AGC kinase PAX; its inhibitor, BRX; and PIP5K enzymes, which promote polar PAX and BRX localization. Because of dynamic PAX-BRX-PIP5K interplay, the net cellular output of this machinery remains unclear. Here we deciphered the dosage-sensitive regulatory interactions between PAX, BRX and PIP5K by their ectopic expression in developing xylem vessels. The data suggest that the dominant collective output of the PAX-BRX-PIP5K module is a localized reduction in PIN abundance. This requires PAX-stimulated clathrin-mediated PIN endocytosis by site-specific phosphorylation, which distinguishes PAX from other AGC kinases. Importantly, ectopic assembly of the PAX-BRX-PIP5K module is sufficient to cause cellular auxin retention and affects root growth vigor by accelerating the trajectory of xylem vessel development. Our data thus provide direct evidence that local manipulation of auxin efflux alters the timing of cellular differentiation in the root.

plant biology↗

bioRxiv2022

The AUX1-AFB1-CNGC14 module establishes longitudinal root surface pH profile

Plant roots navigate in the soil environments following the gravity vector. Cell divisions in the meristem and rapid cell growth in the elongation zone propel the root tips through the soil. Actively elongating cells acidify their apoplast to enable cell wall extension by the activity of plasma membrane AHA H+-ATPases. The phytohormone auxin, central regulator of gravitropic response and root development, inhibits root cell growth, likely by rising the pH of the apoplast. However, the role of auxin in the regulation of the apoplastic pH gradient along the root tip is unclear. Here we show, by using an improved method for visualization and quantification of root surface pH, that the Arabidopsis thaliana root surface pH shows distinct acidic and alkaline zones, which are not primarily determined by the activity of AHA H+-ATPases. Instead, the distinct domain of alkaline pH in the root transition zone is controlled by a rapid auxin response module, consisting of the AUX1 auxin influx carrier, the AFB1 auxin co-receptor and the CNCG14 calcium channel. We demonstrate that the rapid auxin response pathway is required for an efficient navigation of the root tip.

plant biology↗

bioRxiv2022

Gut microbe Lactiplantiballus plantarum undergoes different evolutionary trajectories between insects and mammals

Animals form complex symbiotic associations with their gut microbes, whose evolution is determined by an intricate network of host and environmental factors. In many insects, such as Drosophila melanogaster, the microbiome is flexible, environmentally determined and less diverse than in mammals. In contrast, mammals maintain complex multispecies consortia that are able to colonize and persist in the gastrointestinal tract. Understanding the evolutionary and ecological dynamics of gut microbes in different hosts is challenging. This requires disentangling the ecological factors of selection, determining the timescales over which evolution occurs, and elucidating the architecture of such evolutionary patterns. Here, we employ experimental evolution to track the pace of the evolution of a common gut commensal, Lactiplantibacillus plantarum, within invertebrate (Drosophila melanogaster) and vertebrate (Mus musculus) hosts and their respective diets. While the symbiosis between Drosophila and L. plantarum is mainly determined by host diet, with the host influencing the fitness of its gut microbes only over short timescales, bacterial evolution within the mammalian host follows a divergent evolutionary path. Here, the host and its intrinsic factors play a critical role in selection and influence both the phenotypic and genomic evolution of its gut microbes, as well as the outcome of their symbiosis.

microbiology↗